Concept: Converting a sentence from active voice to passive voice involves changing the focus from the doer of the action (subject) to the recipient of the action (object). The verb form also changes.
Step 1: Identify components of the active sentence
Subject (doer): I
Verb: have seen (Present Perfect tense)
Adverb: already
Object (recipient): this movie
Active sentence: Subject + Verb (have + V3) + Object
\( \rightarrow \) I + have already seen + this movie.
Step 2: Rules for converting to Passive Voice (Present Perfect Tense)
% Option
(A) The object of the active sentence becomes the subject of the passive sentence.
(Active object: "this movie" \(\rightarrow\) Passive subject: "This movie")
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(B) The active verb form "have/has + V3 (past participle)" changes to "have/has + been + V3".
("have seen" \(\rightarrow\) "has been seen" - "has" because "This movie" is singular)
% Option
(C) The adverb "already" is usually placed between the auxiliary verb "has/have" and "been".
% Option
(D) The subject of the active sentence becomes the agent in the passive sentence, usually introduced by "by".
(Active subject: "I" \(\rightarrow\) Passive agent: "by me")
Passive structure: New Subject + has/have + (adverb) + been + V3 + by + Agent.
Step 3: Apply the rules
Active: I have already seen this movie.
New subject: This movie
Auxiliary for singular subject ("This movie"): has
Adverb: already
Add "been".
Past participle of "see": seen
Agent: by me
Passive: This movie has already been seen by me.
Step 4: Compare with the options
(1) This movie is already seen by me. (Incorrect tense. "is seen" is simple present passive.)
(2) This movie has already seen by me. (Missing "been" for present perfect passive.)
(3) This movie was already seen by me. (Incorrect tense. "was seen" is simple past passive.)
(4) This movie has already been seen by me. (Correct present perfect passive form.)